In test devices for testing operating resources in electrical high or medium voltage systems, overvoltages may often occur, which reach or are applied to the interior of the test device through the input sockets or output sockets of the test device and may damage or even destroy there components of the test device, in particular the electronics of the test device. Therefore, overvoltage protection elements such as suppressor diodes or overvoltage gas arrester are installed in conventional test devices in order to protect the test device against such overvoltages or surge voltages.
FIG. 1 schematically shows a test device 1 according to the state of the art. The test device 1 comprises a housing 9 with a plurality of sockets 4 or connection terminals 4, each socket 4 being provided for applying an input signal to be evaluated by the test device 1 or for outputting a test signal by the test device 1 via the respective socket. In the example shown in FIG. 1, for protecting the test device 1 against overvoltages, each of the sockets 4 is connected to a separate overvoltage protection element 3 that is fixed installed in the housing 9.
For example, each protection element 3 may be an overvoltage gas arrester. In the case of overvoltage gas arresters, a small arc ignites if a predetermined voltage is exceeded to discharge the overvoltage to earth. Such overvoltage gas arresters may also be equipped with short-circuit springs. In this case, a spacer melts if the arc occurs too long, and the short-circuit spring can then short-circuit the contacts of the overvoltage gas arrester. Thereby, the overvoltage is reduced to almost zero so that the electronics of the test device can be permanently protected against a malfunction or a fault.
Likewise, suppressor diodes such as TransZorb diodes may be used as protection elements, which have a voltage limiting effect but lead to an electric short-circuit if an overvoltage or overload occurs.
The conventional overvoltage protection arrangements have in common that, if an overvoltage occurs, the protection elements respectively used are destroyed similar to a fuse in order to protect the test device against the overvoltage. To restore or repair a test device in which such an overvoltage protection element has been destroyed by an overvoltage, the housing of the test device has to be opened and an extensive, time-consuming and costly repair has to be carried out.
Therefore, it is the object of the invention to provide a test device for power engineering equipment and a method for manufacturing a test device for power engineering equipment with this problem being resolved and it being possible to restore the test device in a simple and cost-effective way even after a damage or destruction of an overvoltage protection element.